The ratio of the areas of two rectangles is 4 to 5. if the area of the larger rectangle is 135 square feet, what is the area of the smaller rectangle? set up a proportion and solve.

Divide the number 135 and 5. It is going to be 27. Then you multiply 27 times 4. Then you get your answer which is 108.
Proportion set up
small    4                    ?          small
                       
big         5                    135         big         
Cross multiply 4x135= 540
and then divide 540/5= 108